Although there’s been no confirmation of radiation risk in food purchased at Walmart stores, the FDA said that it has detected unsafe levels of cesium-137 contamination at four U.S. ports. This contamination likely suggests that the shrimp was packaged in unsanitary conditions.

The FDA is warning that customers should avoid eating certain frozen shrimp sold at Walmart over concerns that it was possibly exposed to radioactive material.

The amount of Cesium-137 detected within the contaminated shipment would not pose an acute hazard to consumers.